It is doable. I've seen it during my Computer Engineering courses 14 years ago.
Basically you analyze the code for candidates, select a candidate, upload your custom hardware design, run your operation on the hardware, and repeat.
The difficult part is that uploading your hardware to FPGA is in the order of tenths of seconds, which is ages when compared to the nano and micro seconds your CPU works.
So your specific operation must be worthwhile to upload.
A bit of FPGA on your CPU makes it more flexible, for example your could set a profile such as 'crypto' or 'video' to add some specific hardware acceleration to you general purpose CPU.
Imagine your CPU being able to switch your embedded GPU into another CPU core.
Let's say the current zen 2 had an FPGA onboard. AMD could sell you an upgraded design with AV1 support for a few dollars. Most people aren't going to buy a new CPU on the basis of a video decoder, but they'll buy an upgrade to the chip that auto "installs" itself. That's a sale AMD otherwise wouldn't have made.
Basically you analyze the code for candidates, select a candidate, upload your custom hardware design, run your operation on the hardware, and repeat.
The difficult part is that uploading your hardware to FPGA is in the order of tenths of seconds, which is ages when compared to the nano and micro seconds your CPU works. So your specific operation must be worthwhile to upload.
A bit of FPGA on your CPU makes it more flexible, for example your could set a profile such as 'crypto' or 'video' to add some specific hardware acceleration to you general purpose CPU.
Imagine your CPU being able to switch your embedded GPU into another CPU core.